It includes:
-march=atom/-mtune=atom to focus on Atom instructions/optimizations;
-fpmath=sse to generate sse math instructions instead of i387
-m32/-m64/-mx32 support to be able to generate 32/64/x32 code with
single toolchain.

Export CXX_FOR_BUILD otherwise the default g++ can have different
bitness than libiberty.a which is always built in 32-bit for now.
Didn't happen prior to GCC 4.8 because GCC was in C only. GCC from
4.8 now uses C++ as its implementation language

This is required to enforce correct x86 -march/-mtune flags which are
currently hardcoded in gcc (see gcc/config/i386/gnu-user.h). The problem
is that gcc hardcode doesn't work, it is overridden by generic values.
It can be seen with -### option for any compilation.
This patch adds correct configure flags and after it is merged
-march/-mtune flags in gcc can be removed.

Default -mfpmath can't be seen in -### but can be configured as well to
eliminate hardcode.

Also cleanup old flags which didn't work anyway. target_cpu is i686 and
not x86.

The first stage of canadian build "build->target" fails very
frequently during libiberty.a installation in parallel ( > -j4)
The observed sympton is that all threads try to install the
same libiberty.a and latecomer fails in "mv -f" when libiberty.an
is already renamed. eg.

build-gcc.sh passes on --with-sysroot which is really meant for
target. Remove it from "baseargs" to form "host_baseargs"
(borrowed the unused "gold_baseargs") and used it for building
host libraries, otherwise gmp may not have incorrect
dependency_libs= in .libs/libgmpxx.lai.

Before python is also prebuilt, disable python support in gdb-7.x
for now, otherwise gdb-7.x/configure may pick up whatever python
in host and build gdb with hard-wired dependency to specific version
of python.

Let build automatically detect binutils versions and append proper
--enable-gold=xxx options to binutils configuration.
The story is that gcc-4.6 and binutils-2.21 use
--enable-gold=default, our old gcc and binutils use
--enable-gold=both/gold.
With the patch, we pass toolchain configuration --enable-gold=xxx to
gcc, and let build script automatically detect binutils version
number and append proper --enable-gold=xxx to binutils configuration.

The problem was caused by undefined $(INSTALL). The patch attempts to
configure `install' program by autotool in order to set $(INSTALL)
properly and replace $(INSTALL) -m 644 with multi-platform friendly
$(INSTALL_DATA).

GCC 4.5 and up supports graphite optimization, and cloog and ppl
are required. This change attempts to support some combinations
of ppl and cloog/cloog-ppl libraries. Since cloog and ppl are
written in C++, it implies we might suffer from C++ ABI breakage
problems when host environment changes, that is a well-known issue
in GNU/Linux distributions. Thus, we have to link to static C++
runtime library (libstdc++) to avoid depending on the host version.